In a single tooth implant as is known from DE 40 28 855 C2 and is also the subject-matter of DE 195 09 762.9-32 rotation prevention is effected in such a way that the base body positively locking elements at the bottom of the annular recess of the base body and the spacer sleeve positively locking elements which are complementary thereto are provided at the cervical edge of the centering shoulder of the spacer sleeve. From the point of view of production engineering such positively locking elements can only be produced with comparative difficulty, while in many situations of use it is not especially desirable that it is not the full depth of the annular recess or the centering shoulder that is available for centering, fixing and securing the spacer sleeve relative to the base body.
Another dental implant as is provided in DE 37 35 378 also involves difficulties of a similar kind, which are due to the fact that in that case also the positively locking elements of the base body are disposed at a spacing from the coronal edge thereof within a blind bore in the base body.
DE 41 27 839 A1 discloses an implant base body whose central annular recess has a positively locking element which directly adjoins the coronal edge of the base body, wherein the positively locking element is of a groove-shaped configuration and the holding portion to be inserted in the base body is of a configuration complementary thereto. A separate implant post is not provided in that case.
DE 195 34 979 C1 discloses a single tooth implant in which the positively locking elements of the base body are arranged directly adjoining the coronal edge thereof with a corresponding arrangement and configuration of the abutment positively locking elements which are complementary thereto. Because the entire depth of the annular recess of the base body is available for centering and guiding the abutment that is said to give markedly improved stability in the connection between the spacer sleeve and the base body with a greater degree of design freedom in the nature of the division and the shaping of the positively locking elements.